The present invention is directed to an apparatus for analyzing the motion, impulse and impact force when a ball is struck by a swinging sporting implement. Specifically, the present invention is directed to an apparatus and method of determining the quality of the swing impulse and impact force of a swinging baseball bat, golf club, tennis racquet and the like. The apparatus of the present invention processes data to indicate the quality of the swing and the impact force in order to diagnose problems and provide guidance for improving swing quality and to maximize impulse and impact force.
There are a number of prior art devices which have been developed to analyze swing quality in sports such as golf and tennis. Typically, these prior art devices and methods have been generally applied to golfing. Several diagnostic systems are available for analyzing a golf swing. In the more recent of these devices, club position is sensed by use of a light source and multiple numbers of light sensors An example of such a device is manufactured by Sports Technology of Essex, Conn. This apparatus can be used when the position of the ball is fixed and the point of impact is known. The device provides data on the average velocity of the swing in the vicinity of the contact point, the direction of the swing, and the club face angle. The device utilizes a significant amount of hardware, requires installation time, and is affected by the level of ambient lighting. Further, the apparatus cannot be used if the ball position is not fixed, as is the case when a baseball or tennis ball is struck. Finally, the device does not provide continuous data on the motion of the club.
Another type of prior art apparatus for measuring bat motion utilizes high speed photography. These methods require sophisticated and expensive equipment and do not provide instantaneous results. An additional type of prior art apparatus utilizes high speed video photography to measure bat position as a function of time. An example of such an apparatus is the Kodak Ektapro 1000 motion analyzer. The positional data obtained from this apparatus can be processed to provide velocity and acceleration data. However, the use of high speed video photography is expensive and requires trained personnel.
Further types of diagnostic or instructional aid devices utilize a modified club, or require the addition of belts and harnesses. Examples of such devices are disclosed in U.S. Pat. Nos. 4,582,325 and 4,598,911. These devices are cumbersome and by their very nature, do not replicate the motion of a real bat or club.
A device which utilizes an accelerometer is disclosed in U.S. Pat. No. 4,088,324. In this apparatus, the accelerometer output is processed and displayed by means of circuits built into a golf club. Only a suitably modified golf club can be used for tests. The device disclosed in this patent also focuses on the peak value of the acceleration, and this value is used to predict the distance the ball would travel.
The present invention is directed toward improving over the prior art devices, and provides a significant leap toward providing identifiable and empirically testable swing parameters. With the apparatus of the present invention, an accelerometer is mounted on the bat, racquet or other swingable sports implement. A suitable commercially available sensor as small as 0.14-by-0.14-by-0.27 inch in size may be utilized. The signal from the accelerometer is transmitted to an electronic processor via wires, or, alteratively, via an rf signal. In the latter case, an rf transmitter is built into the sensor installation mounted on the bat. The data processed produces various outputs which are useful in analyzing the swing and impact force. These include peak velocity, peak acceleration, impulse magnitude, duration of contact, time of contact (with respect to peak velocity), velocity as a function of time and the displacement as a function of time. These data are available as digital and graphic output in less than one minute from the completion of the swing. The apparatus can be housed in a cabinet the size of a typical lap-top computer which weighs less than 15 pounds. The apparatus may be battery operated and thus is easily transportable
As a diagnostic tool, the apparatus can be used to characterize a batter's swing when he or she is hitting well, and then compared to his or her swing when he or she is not hitting well. A comparison of these data could indicate the difference in the swing and the interpretation of the differences could be used to correct the swing. Alternatively, the swing of any batter could be characterized and constructive changes in his swing proposed based upon the interpretation of these data. With the addition of velocity measurement equipment, the batter's contribution to the mass of the system can be determined.
The present application further discloses a bat or implement swing machine. The machine makes it possible to reproducibly strike a ball or object with a bat in a predetermined manner. This machine helps calibrate the analyzing apparatus, perform test studies, study the effect of impact location on batting effectiveness, and study the effect of transducer or acceleometer placement on sensor readout.
In view of the above, it is a object of the present invention to provide an apparatus which can translate swing acceleration into a plurality of swing performance parameters which can be utilized for instructional or diagnostic purposes.
It is a further object of the present invention to provide an apparatus which produces a unique swing signature which can be analyzed and utilized for instructional and diagnostic purposes.
It is still a further object of the present invention to provide a universal sensor which can easily be used interchangeably on a variety of sports implements.
It is still a further object of the present invention to provide a swing analyzer which can transmit acceleration data either through a hard-wired coupling or via an rf transmitter.
It is yet a further object of the present invention to provide a swing analyzer which, when utilized in conjunction with speed measuring apparatus, can be utilized to calculate the contribution of the player to the effective mass of the system.
It is still a further object of the present invention to provide an apparatus which can reproducibly strike a ball with an implement in a predetermined manner in order to calibrate the analyzer, perform studies and tests, and test accelerometer wear.